An ever-increasing number of electrical household appliances are commonly employed in every domestic environment. The correct operation of most appliances is very important, particularly when nobody is at home (such as during a vacation).
For example, a prolonged outage in a power supply network feeding the appliances may bring about serious damages. A typical problem is that of a freezer containing frosted food. In this case, the food may be defrosted during the outage and then frozen again when the power supply is restored; as a consequence, the food is no more suitable for eating. However, a user returning home after several days of vacation is completely unaware of the situation, with serious risks of poisoning.
Several types of devices for detecting outages in the powers supply network have been proposed in the last years. All the devices known in the art trigger an alarm when the outage is detected; for example, a warning LED is switched on, so as to inform the user that an outage has occurred when he or she was not at home.
A drawback of the solutions known in the art is that they are completely ineffective in monitoring operation of the appliances. Particularly, no information is provided to the user about any critical condition that may have occurred during his or her absence.